Anilide derivatives as antidepressants

ABSTRACT

Anilide derivative compounds of the formula ##STR1## e.g., trans-N-(2-hydroxycyclopentyl)-3&#39;,4&#39;-dichloropropionanilide, have been found to possess potent Central Nervous System (CNS) antidepressant properties. 
     These compounds are promising antidepressant drugs which are characterized by less toxicity than imipramine, and long-acting activity which may allow longer durations between administrations, e.g., once a day. Pharmaceutical compositions containing these compounds and a process for treating conditions of depression with these compositions are also disclosed.

CROSS REFERENCES TO OTHER APPLICATIONS

This is a division of application Ser. No. 796,989, filed May 16, 1977,now U.S. Pat. No. 4,128,663, which was a continuation-in-part ofapplication Ser. No. 777,599, filed Mar. 15, 1977, now abandoned, whichwas a continuation-in-part of Ser. No. 746,191, filed Nov. 30, 1976, nowabandoned.

INTRODUCTION

This invention relates to some cycloaliphatic amides which have centralnervous system pharmaceutical utility. More particularly, this inventionprovides some new N-(2-hydroxy, 2-alkyloxy-, 2-aralkyloxy-, or 2-acyloxycyclopentyl)-N-alkanoylanilide derivative compounds, which have beenfound to have potent CNS antidepressant properties, which make themuseful as antidepressant drugs when formulated into usefulpharmaceutically usable composition forms and administered inappropriate dosages.

BACKGROUND OF THE INVENTION

W. G. Stoil et al., in Helvetica Chemica Acta, Vol. 34 (1951), pp. 1937to 1943, disclose N-[2-(dimethylamino)cyclohexyl]aniline and proceduresfor making it from N-(2-hydroxycyclohexyl)aniline and suggest that thecompounds therein have antihistamine pharmacological properties, butnothing is said about the compounds of this invention or their use asantidepressant drugs.

J. W. Lewis et al., in an article entitled "The Reactions of AromaticNitroso-compounds with Enamines. Part I. The Reaction of NitrosobenzeneWith 1-Morpholin-1-cyclohexene" in J. Chem. Soc. (London) (1972),Perkins Transactions I, Part III, pp. 2521-2524, discloses inter aliaN-(2-morpholin-1-yl-cyclohexyl)phenylhydroxylamine and its hydrochloridesalt, but it does not disclose or suggest the alkanoyl-anilidederivatives of this invention or their antidepressant properties.

J. W. Lewis et al., in an article entitled "Chemistry and BiologicalActivity of N-Substituted Hydroxylamines" in J. Pharmaceutical Sciences,December, 1974, Vol. 63, No. 12, pp. 1951-1953, discloses someN-Aryl-hydroxylamines such asN-[2-(N-pyrrolidinyl)cyclohexyl]-N-phenylhydroxylamine but these do nothave useful CNS properties. Diuretic activity is alleged therein for thealcohols such as [2-(N-piperidinylcyclohexyl)(4-methoxyphenyl)methanol]and when the alcohol is acetylated, CNS depressant activity is said toappear. It also discloses the reaction of propionyl chloride withN-[2-(N-piperidinyl)-1,1-dimethylethyl]-N-phenylhydroxylamine to formthe N-chloro compound which is then converted to a mixture ofchlorinated aniline derivatives. That publication does not teach thecompounds disclosed herein, how to make them, nor does it suggest theantidepressant properties which have been found for the compoundsdisclosed and claimed herein.

Szmuszkovicz U.S. Pat. No. 3,510,492 discloses and claims some2-anilino- and 2-anilinomethylcycloalkylamines which are useful asantidiabetic drugs in that they can be administered in low dosages toreduce blood sugar. In column 3 this Szmuszkovicz patent discloses aMethod B for preparing the N-(2-aminocycloalkyl)anilines of thatinvention and discloses the making and use of someN-(2-oxocycloalkyl)anilines (structure VI) compounds as chemicalintermediates therein. Further, in column 3 thereof, that Szmuszkoviczpatent discloses some N-(2-carboxycycloalkyl)anilines (structure XI) aschemical intermediates in the process for preparing Szmuszkovicz'scis-N-(2-aminocycloalkyl)anilines of that patent. In column 10 thereof,Szmuszkovicz discloses some 2-hydroxycycloalkylamines as chemicalintermediates in disclosing how to prepare the starting materials forthe compounds claimed therein. However, that patent does not disclose orsuggest the compounds of this invention, how to prepare them or whatpharmaceutical utilities they might have.

In my patent applications Ser. Nos. 746,191, filed Nov. 30, 1976, nowabandoned and 777,759, filed Mar. 15, 1977, now abandoned I havedisclosed and claimed the use of someN-(2-aminocyclopentyl)-N-alkanoxylanilides and their 2-N-oxides asantidepressant drugs. Those compounds are characterized by acyclopentane-1,2-di-nitrogen structure, whereas the compounds of thisinvention are characterized by having an oxygen bonded to thecyclopentane ring carbon atom in the 2-position thereof.

Those in the pharmaceutical, chemical and pharmacological arts continueto need and look for active and more economical drugs which will haveuseful Central Nervous System (CNS) drug properties.

OBJECTS OF THE INVENTION

It is an object of this invention to provide some newN-(2-hydroxycyclopentyl)anilide compounds and ether and esterderivatives thereof which have promising CNS antidepressant drugproperties and uses as chemical intermediates to prepareN-(2-aminocyclopentyl)anilide antidepressant drug compounds.

It is a more specific object of this invention to provide some newN-(2-hydroxycyclopentyl)-N-alkanoylanilides which are useful asantidepressant drugs, the preferred compounds having less toxicity thanimipramine and long activity which allows longer durations betweenadministrations.

It is another object of this invention to provide compositions, usefulin pharmaceutical dosage unit form, for treating conditions ofdepression in mammals including humans comprising anN-(2-hydroxycyclopentyl)-N-alkanoylanilide, or an ether or esterthereof, as described herein, in a pharmaceutical carrier.

It is another object of this invention to provide a process or methodfor treating conditions of depression in mammals including humans withan effective, non-toxic amount of these compositions containing anN-(2-hydroxycyclopentyl)-N-alkanoylanilide, or an ether or esterthereof.

Other objects, aspects and advantages of this invention will becomeapparent from reading the remaining specification and claims whichfollow.

SUMMARY OF THE INVENTION

This invention provides some N-(2-hydroxycyclopentyl)-N-alkanoylanilidesand ether and ester compounds, as described more fully below, as newcompounds. These compounds have been found to be useful as CNSantidepressant drugs, in standard laboratory animals to measure thoseproperties. These new compounds are also chemical intermediates for thepreparation of N-(2-aminocyclopentyl)-N-alkanoylanilide antidepressantdrug compounds referred to in my above-identified patent applications.All of these compounds are characterized by lower toxicity thanimipramine and have long acting activity which permits longer durationbetween administrations than other known anti-depressant drugs.

This invention also includes pharmaceutical compositions containing anN-(2-hydroxycyclopentyl)-N-alkanoylanilide, or an ether or an esterthereof, in a pharmaceutical carrier, which compositions are useful inpharmaceutical dosage unit form for treating conditions of depression inmammals including humans. This invention also includes a method of usingthese compositions to treat conditions of depression in mammalsincluding humans by administering to such a patient suffering conditionsof depression an effective, nontoxic amount of anN-(2-hydroxycyclopentyl)-N-alkanoylanilide or an ether or ester thereof,as described herein, or a pharmaceutical carrier.

DETAILED DESCRIPTION OF THE INVENTION

More specifically, this invention provides compounds of the formula##STR2## wherein the heavy dot • at the 1-position carbon atom of thecyclopentyl ring denotes trans-configuration relative to the oxygengroup (--OR₁) in the 2-position of the cyclopentyl ring:

R is hydrogen,

C₁ to C₃ -alkyl, C₃ to C₆ -cycloalkyl, C₁ -C₃ alkyloxy, C₂ to C₄-alkenyl, or C₁ to C₃ -alkyloxymethyl;

R₁ is hydrogen, C₁ to C₃ -alkyl, C₃ to C₅ -(allylic)alkenyl,

the benzyl group ##STR3## where Y' and Z' are as defined below, or thegroup ##STR4## wherein R₂ is hydrogen, C₁ to C₃ -alkyl, benzyl, asindicated above, or a phenyl group ##STR5## wherein Y' and Z' are asdefined below; and each of Y, Z, Y' and Z' is a substituent, preferablyat least one of which is in the 3- or 4-position, having a Hammettsubstituent constant, sigma meta (σ_(m)), in the range of from about-0.1 to +0.6 or a Hammett substituent constant sigma para (σ_(p)) in therange of from about -0.3 to about +0.8 as compiled by A. G. Gordon andR. A. Ford in The Chemist's Companion: A Handbook of Practical Data,Techniques and References, J. Wiley & Sons, N. Y. (1972) pp. 144 to 155,for example, hydrogen, a halogen having an atomic number of from 9 to35, trifluoromethyl, C₁ to C₃ -alkyl, and C₁ to C₃ -alkyloxy, azido, orsome equivalent group, and the Y, Z or Y' and Z' can be the same ordifferent, and Y, Z or Y' and Z' are not necessarily the same at thesame time.

The compounds in their crystalline state can be isolated from reactionmixtures as solvates, i.e., with a discrete quantity of solvent, e.g.,water, ethanol, and the like, associated physically, and thus thesolvent is removable without effective alteration of the chemical entityper se, and are included with the compounds per se herein.

In the above formula I compounds the term "C₁ to C₃ -alkyl" meansmethyl, ethyl, n-propyl and isopropyl; the term "C₃ to C₆ -cycloalkyl"means cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl groups; theterm "C₂ to C₄ -alkenyl" includes, for example, vinyl, allyl, 2-butenyl,1-propenyl, and the like. The halogens having atomic numbers of from 9to 35 are fluorine, chlorine and bromine. The term "C₃ to C₅-(allylic)alkenyl" includes the non-adjacent double bond groups, e.g.,allyl, 2-propenyl, 2-methyl-2-butenyl, 2-pentenyl, and the like; theterm "C₁ -C₃ alkyloxy" includes, e.g., methoxy, ethoxy, propoxy; theterm "C₁ -C₃ alkyloxymethyl" includes, e.g., methoxymethyl,ethoxymethyl, n-propyloxymethyl, and the like.

A preferred group of compounds of formula I are those wherein R is C₁ toC₃ -alkyl, R₁ is hydrogen and at least one of Y and Z is a halogenhaving an atomic number of from 9 to 35, preferably in the 3- or4-positions, trifluoromethyl, or a C₁ -C₃ -alkyl. Examples of suchcompounds include the trans isomers of:

3,4-Dichloro-N-(2-hydroxycyclopentyl)propionanilide,

4-Bromo-N-(2-hydroxycyclopentyl)propionanilide,

3,4-Difluoro-N-(2-hydroxycyclopentyl)butyranilide,

3-Trifluoromethyl-N-(2-hydroxycyclopentyl)propionanilide,

3-Bromo-4-ethyl-N-(2-hydroxycyclopenty)acetanilide,

4-Chloro-3-methyl-N-(2-hydroxycyclopentyl)propionanilide,

and the like.

Another preferred group of such formula I compounds are those wherein Ris C₁ to C₃ -alkyl, R₁ is C₁ to C₃ -alkyl and at least one of Y and Z isa halogen having an atomic number of from 9 to 35, preferably in the 3-or 4-position, trifluoromethyl, or a C₁ -C₃ alkyl. Examples of suchcompounds, include the trans isomers of:

3,4-Dichloro-N-(2-methoxycyclopentyl)propionanilide,

4-Bromo-N-(2-ethoxycyclopentyl)propionanilide,

3-Trifluoromethyl-N-(2-propoxycyclopentyl)butyranilide, and

3-Chloro-4-methyl-N-(2-methoxycyclopentyl)propionanilide, and the like.

Another preferred group of the formula I compounds are those wherein Ris C₃ to C₆ -cycloalkyl, R₁ is C₁ to C₃ -alkyl and at least one of Y andZ is a halogen having an atomic number of from 9 to 35, preferably inthe 3- or 4-position, trifluoromethyl, or C₁ -C₃ alkyl. Examples of suchcompounds include:

3,4-Dichloro-N-(2-methoxycyclopentyl)cyclopropanecarboxanilide,

4-Bromo-N-(2-ethoxycyclopentyl)cyclobutanecarboxanilide,

3-Trifluoromethyl-N-(2-propoxycyclopentyl)cyclopentanecarboxanilide,

3-Chloro-4-methyl-N-(2-methoxycyclopentyl)cyclohexanecarboxanilide, andthe like.

Another preferred group of formula I compounds of this invention arethose wherein R is C₁ to C₃ -alkyl, R₁ is C₁ to C₃ -alkanoyl and atleast one of Y and Z is a halogen having an atomic number of from 9 to35, preferably in the 3- or 4-position, trifluoromethyl, or C₁ -C₃alkyl. Examples of such compounds include the trans isomers of:

3,4-Dichloro-N-(2-acetoxycyclopentyl)-N-acetanilide,

3,4-Dichloro-N-(2-acetoxycyclopentyl)-N-propionanilide,

4-Bromo-N-(2-propionoxycyclopentyl)-N-propionanilide,

3-Trifluoromethyl-N-(2-formyloxycyclopentyl)-N-propionanilide, and

3-Chloro-4-methyl-N-(2-acetoxycyclopentyl)-N-propionanilide.

The various compounds of formula I above can be prepared by a series ofprocess steps starting from 1,2-cyclopentene oxide and the desiredaniline or substituted aniline to form thetrans1-anilino-2-hydroxycyclopentanes of the formula ##STR6## Thesetrans 1-anilino-2-hydroxycyclopentanes are then reacted with an R--C(O)Xacyl halide or R--C(O)--O--C(O)--R acid anhydride to form theN-acylamides of the formula ##STR7## wherein R, Y and Z are as definedabove, and may or may not be the same as R₂, depending upon theester-amide product desired. If it is desired to proceed further toprepare the alcohol-amide products, the above ester amides are subjectedto basic hydrolysis to form the new compounds of the formula ##STR8##wherein R, Y and Z are as defined above. These alcoholamide products maybe used as the products of this invention or they can be used aschemical intermediates by reaction thereof with an R₁ X halide whereinR₁ is as defined above and X is chlorine or bromine to form theether-amide compounds of the formula ##STR9## wherein R₁ denotes theresidue of the ether groups defined above, and R, Y and Z are as definedabove, or the alcohol-amide compounds can be reacted with an R₂ --C(O)Xacyl halide to form new ester-amides of the formula where R₂ denotes theresidue of the N-acyl groups defined above, and R, Y and Z are asdefined above. This latter esterification step is needed only when theR₂ --C(O)-acyl group is not to be the same as R--C(O)-acyl group whichis obtained earlier in the process.

Examples of anilines that can be used for reactio-with the1,2-cyclopentene oxide to form the 1-(anilino)2-hydroxy cyclopentaneintermediates for making the N-(2-hydroxycycloalkyl)-N-anilides of thisinvention include:

aniline,

3,4-dichloroaniline,

3,5-dichloroaniline,

3-methyl-4-chloroaniline,

3-chloro-4-methylaniline,

3,4-dibromoaniline,

4-bromoaniline,

4-azidoaniline,

3-trifluoromethylaniline,

4-trifluoromethylaniline,

3-methoxyaniline,

3,5-dimethylaniline,

3-ethylaniline,

2-chloro-4-methylaniline,

3,4-dimethoxyaniline,

3-chloro-4-fluoroaniline,

3,4-dimethylaniline,

4-propylaniline, and the like.

Examples of orthoformates and carboxylic acid anhydrides which can beused to prepare the compounds of this invention include tri-C₁ to C₃-alkylorthoformate, such as trimethylorthoformate, acetic anhydride,propionic anhydride, n-butanoic acid anhydride, isobutanoic acidanhydride, cyclopropanecarboxylic acid anhydride, cyclobutanecarboxylicacid anhydride, cyclopentanecarboxylic acid anhydride,cyclohexanecarboxylic acid anhydride, acrylic anhydride, 2-butenoic acidanhydride, 2-pentenoic acid anhydride, and the like. The carboxylic acidhalides useful for acylating the anilino nitrogen or the 2-hydroxy groupof the cycloalkyl moiety include acetyl chloride or bromide, propionylchloride or bromide, butyryl chloride or bromide, cyclobutanecarbonylchloride or bromide, cyclohexanecarbonyl chloride or bromide, acryloylchloride or bromide, methoxyacetyl chloride 2-butenoyl chloride orbromide, benzoyl chloride or bromide, phenylacetyl chloride and suchphenylacetyl or benzoyl halides substituted on ring carbons thereof asdefined above for Y' and Z', e.g., 4-trifluoromethylbenzoylchloride orbromide, 4-bromobenzoyl bromide, 3-trifluoromethylphenylacetylchloride,3,4-dichlorophenylacetyl chloride, 3,4-dichlorobenzoyl chloride and thelike.

Useful reagents for forming ether groups of the 2-hydroxycycloalkylmoieties of these compounds include methylbromide, methyl iodide, ethylbromide or iodide, propyl bromide, 2-propenyl chloride or bromide,2-butenyl bromide or iodide, 2-methyl-2-butenyl bromide, 2-pentenylchloride or bromide, benzyl chloride or bromide, and benzyl substitutedas defined for Y' and Z' above, such as, 3-trifluoromethylbenzylchloride or bromide, 4-azidobenzyl chloride or bromide,3,5-dimethylbenzyl iodide or bromide, 3,4-dichlorobenzyl iodide,4-bromobenzyl bromide, 4-chlorobenzyl bromide or iodide and the like.Methods for ether preparation from alcohols and halides are known in theart and examples can be found in Buehler and Person, "Survey of OrganicSyntheses", Wiley (1970), pp. 287-289. We have found that the mostpotent anti-depressant compounds are made from those compounds having anN-propionyl moiety so that in the formula I compounds, R is preferablyethyl.

Starting materials useful for purposes of this invention, if notcommercially available, can be made by standard methods known in thechemical art.

If desired, the formula I compounds of this invention can be resolvedinto their respective d- and l-optical isomers by methods known in theart, for example in Organic Syntheses, Coll. Vol. 1, p. 418 (1946). Theoptical resolution of the compounds of the present invention can be doneby at least two different routes:

By the first method for resolving the compounds of this invention, forexample, one of the 2-hydroxycyclopentyl anilide compounds can beconverted into its optically active diastereomeric salts by reactionwith an optically inert esterifying agent (e.g., phthalic anhydride)followed by reaction with an optically active base, e.g., brucine, in amanner standard in the isomer resolution art. These diastereomeric saltscan then be separated by conventional means such as differentialcrystallization. Diastereomeric salts have different crystallizationproperties, which are taken advantage of in this separation. Onneutralization of each diastereomeric salt with aqueous acid followed byhydrolysis with base the corresponding optically active isomer of thefree 2-hydroxycyclopentyl anilide can be obtained which can subsequentlybe converted to the corresponding optically active 2-ethers or 2-esters.By the second method, which in the case of some of these compounds ispreferred, the N-(2-hydroxycyclopentyl)anilide derivative compound canbe resolved into its respective d- and l-isomers by first resolving theunsymmetrically substituted 2-hydroxycyclopentylaniline into itsrespective d- and l-isomers by treatment with the resolving agent, suchas optically active camphosulfonic acid, crystalization, separation andregeneration of each of the d- and l-isomers and then reacting therespective resolved d- or l-2-hydroxycyclopentylaniline startingmaterial with the selected orthoformate or carboxylic acid anhydride orcarboxylic acid halide to form the respective d- or l-isomers of theformula I compounds as the diacylated compounds which on subsequentbasic hydrolysis give the respective optically active2-hydroxycyclopentyl anilides which then can be converted as describedin the Examples to other 2-ethers and 2-esters.

In the use of these compounds of formula I as anti-depressant drugs, theselected compound of formula I which is to be the anti-depressant activeingredient is mixed with suitable pharmaceutical diluents to obtainpharmaceutical compositions suited for oral, parenteral and rectal usein dosage unit form, e.g., tablets, powder packets, cachets, dragees,capsules, solutions, suspensions, sterile injectable forms,suppositories, bougies and the like. Suitable diluents or carriers suchas carbohydrates (lactose), proteins, lipids, calcium phosphate, cornstarch, stearic acid, methylcellulose and the like may be used ascarriers or for coating purposes. Water and oils, e.g., coconut oil,sesame oil, safflower oil, cottonseed oil, peanut oil may be used forpreparing solutions or suspensions of the active drug. Sweetening,coloring and flavoring agents may be added. The specifications for thedosage unit forms of these formula I compounds will vary somewhat fromcompound to compound and dependent upon the physical characteristics ofthe formula I compound, the particular patient's weight and age, and theparticular effect sought to be achieved. The pharmaceutical dosage unitforms of these compounds are prepared in accordance with the precedinggeneral description to provide from about 4 to about 400 mg. of theformula I compound per dosage unit form. The amount of the formula Icompound prescribed in pharmaceutical dosage form is that amountsufficient to obtain in the patient a relief from the condition ofdepression effect at a non-toxic dosage level.

The following detailed procedures and examples further describe andillustrate how to make and use the starting amines and the compounds ofthis invention. All temperatures are in degrees Celsius unless otherwiseindicated. For brevity, the term THF means tetrahydrofuran, DMF meansN,N-dimethylformamide, NMR means nuclear magnetic resonance spectrum, IRmeans infrared spectrum, UV means ultraviolet spectrum, ether meansdiethyl ether, NaOH means sodium hydroxide, MgSO₄ means anhydrousmagnesium sulfate, and MeOH means methanol.

EXAMPLE 1 Trans-N-(2-hydroxycyclopentyl)-3,4-dichloropropionanilide

Part A

A solution of 3,4-dichloroaniline (200 g., 1.23 mole), cyclopenteneoxide (400 ml.) and concentrated HCl (2 ml.) is heated at refluxtemperature for seven (7) days. The unreacted epoxide is evaporated at60° C. and the residue is treated with excess ethereal HCl, and a syrupresults. This is washed with 1000 ml. of ether. The residue iscrystallized and recrystallized from methanol/ether (1/5.5, v/v) to give170.0 g. (49% yield) oftrans-3,4-dichloro-N-(2-hydroxycyclopentyl)aniline, hydrochloride salt.

Part B

A mixture of the amino alcohol,trans-N-(2-hydroxycyclopentyl)-3,4-dichloroaniline, released from itshydrochloride salt with 10% sodium hydroxide (61.5 g., 0.25 mole) andpropionic anhydride (130 g., 1.0 mole) is heated on a stream bath for 72hours. Water (250 ml.) is added and heating is continued for one hour.The mixture is cooled in an ice bath and then made basic by addition of40% sodium hydroxide (140 ml.). The mixture is extracted with ethylether, the ether extract washed with brine, dried over magnesium sulfateand evaporated to a brown oily residue (95.0 g.) of the crudeamide-ester, N-(2-acetoxycyclopentyl)-N-3,4-di-chloropropionanilide.This crude amine-ester oil is dissolved in a solution of potassiumhydroxide (17.0 g., 85%, 0.25 mole) in 95% ethanol (250 ml.) and kept atroom temperature for 3 hours. The solution is subjected to evaporationto remove solvent. The residue is treated with ether and extracted withwater, 10% hydrochloric acid solution and brine. The organic layer isdried and evaporated to a brown solid. Recrystallization of the brownsolid from an ether-petroleum ether mixture (b.p. 30°-60° C.) gives thetitled compound, 49.5 g., 66% yield, m.p. 105° C., UV, IR, NMR and massspectra are consistent with the assigned structure. Anal. calcd. for C₁₄H₁₇ Cl₂ NO₂ :

Calcd.: C, 55.64; H, 5.67; N, 4.64; Cl, 23.46. Found: C, 55.84; H, 5.57;N, 4.81; Cl, 23.50.

EXAMPLE 2 Preparation oftrans-3,4-dichloro-N-(2-methoxycyclopentyl)propionanilide

A mixture of 6.04 g. (0.02 mole) oftrans-3,4-dichloro-N-(2-hydroxycyclopentyl)priopionanilide, (Example 1)11.36 g. (0.08 mole) of methyl iodide, and 1.92 g. (50% dispersion, 0.04mole) of sodium hydride in 75 ml. of DMF is stirred at room temperatureovernight. The mixture is filtered through a filter aid (Celite®) andthe DMF solvent is removed from the filtrate by distillation at reducedpressure. The residue is dissolved in 250 ml. of ethyl ether and thissolution is washed twice with water, followed by saturated aqueoussodium chloride solution, dried over anhydrous magnesium sulfate andconcentrated to a yellow oil. Chromatography on silica gel withchloroform as eluent gives a center fraction (single component by thinlayer chromatography) which is distilled to give 3.2 g. (50% yield) ofthe titled compound, b.p. 145°-150° C./0.01 mm. Hg.

Anal. calcd. for C₁₅ H₁₈ NCl₂ O₂ : Calcd.: C, 56.97; H, 6.06; N, 4.43;Cl, 22.42. Found: C, 57.02; H, 6.65; N, 4.37; Cl, 22.13.

EXAMPLE 3 Preparation of trans-N-(2-hydroxycyclopentyl)-propionanilide

Following the procedure of Example 1, but substituting astoichiometrically equivalent amount of aniline for 3,4-dichloroanilineand adding a small quantity of water, there is obtained the titledcompound, b.p. about 140° C./0.2 mm. Hg., 2.7 g., 36% yield.

Anal. calcd. for C₁₄ H₁₉ NO₂ : Calcd.: C, 72.07; H, 8.21; N, 6.01.Found: C, 72.15; H, 8.37; N, 5.90.

EXAMPLE 4 Preparation oftrans-3,4-dichloro-N-(2-acetoxycyclopentyl)propionanilide

A mixture of trans-3,4-dichloro-N-(2-hydroxycyclopentyl)propionanilide(3.02 g., 0.01 mole) (Example 1) and 10 ml. of acetic anhydride isheated on a steam bath for 3 hours. Additional heating for 1 hour isdone after addition of 50 ml. of water. The reaction mixture is cooled,diluted with 50 ml. of water, and extracted with 200 ml. of ether. Theether extract is washed successively with water, saturated aqueoussodium bicarbonate solution and saturated aqueous sodium chloride, driedover anhydrous magnesium sulfate and is concentrated to a yellow oil.Distillation at reduced pressure gives 3.0 g. (37% yield) of the titledcompound, b.p. 160°-165° C./0.3 mm. Hg. The Nuclear Magnetic Resonance(NMR) and IR spectra are consistent with the assigned structure.

Anal. calcd. for C₁₆ H₁₉ NCl₂ O₃ :

Calcd.: C, 55.82; H, 5.56; N, 4.07; Cl, 20.60. Found: C, 55.77; H, 5.51;N, 4.02; Cl, 21.07.

EXAMPLE 5 Preparation oftrans-3,4-dichloro-N-(2-acetoxycyclopentyl)acetanilide

A mixture of 0.015 mole oftrans-3,4-dichloro-N-(2-hydroxycyclopentyl)aniline (Example 1, Part A)free base and 25 ml. of acetic anhydride is heated on a steam bathovernight. After addition of 200 ml. of water, heating is continued for30 minutes. The reaction mixture is cooled and extracted with 300 ml. ofethyl ether. The ether layer is washed sequentially with 100 ml. of 15%aqueous NaOH, 100 ml. of water, and 100 ml. of brine; the ether layer isthen dried (MgSO₄) and evaporated to a yellow oil which is distilled togive 3.20 g. (66% yield) of the titled compound (b.p. 160° C./0.2 mm.Hg.).

Anal. calcd. for C₁₅ H₁₇ NCl₂ O₃ : Calcd.: C, 54.56; H, 5.19; N, 4.24;Cl, 21.47. Found: C, 54.39; H, 5.21; N, 4.27; Cl, 22.00.

EXAMPLE 6 Alternate preparation oftrans-2-(3,4-dichloroanilino)cyclopentanol

A solution of 50.0 g. (0.31 mole) of 3,4-dichloroaniline in100 ml. ofcyclopentene oxide is refluxed for 7 days. The solution is evaporatedand the residue triturated with 250 ml. of petroleum ether (b.p. 30°-60°C.) five times to remove unreacted 3,4-dichloroaniline. The residue istreated with excess ethereal hydrogen chloride and the resulting crudehydrochloride salt is recrystallized twice from a methanol/ethyl ethermixture to give trans-2-(3,4-dichloroanilino)cyclopentanol, 38.7 g. (44%yield), m.p. 167°-168° C. The ultraviolet, infrared and nuclear magneticresonance spectra are consistent with the structure of this product.

Anal. calcd. for C₁₁ H₁₃ Cl₂ NO.HCl: Calcd.: C, 46.75; H, 4.99; N, 4.96;Cl, 37.64. Found: C, 46.79; H, 5.03; N, 4.97; Cl, 37.20.

EXAMPLE 7

Following the procedure of Example 1 but initially substituting astoichiometrically equivalent quantity of 4-bromoaniline for3,4-dichloroaniline there is obtainedtrans-4-bromo-N-(2-hydroxycyclopentyl)propionanilide.

EXAMPLE 8

Part A

Following the procedure of Example 1 but initially substituting astoichiometrically equivalent quantity of 3-trifluoromethylaniline for3,4-dichloroaniline, there is obtained3-trifluoromethyl-N-(2-hydroxycyclopentyl)propionanilide.

Part B

Following the procedure of Example 2 but substituting astoichiometrically equivalent quantity of benzyl iodide (preparedseparately, or in situ from benzyl bromide and crystalline potassiumiodide) for methyl iodide, and the propionanilide from Part A (above)for the 3,4-dichloro-N-(2-hydroxycyclopentyl)propionanilide, there isobtained 3-trifluoromethyl-N-(2-benzyloxycyclopentyl)-propionanilide.

EXAMPLE 9

Following the procedure of Example 4 but initially substituting4-bromobenzoylchloride for acetic anhydride there is obtained3,4-dichloro-N-[2-(4-bromobenzoyloxy)-cyclopentyl]propionanilide.

EXAMPLE 10

Part A

Following the procedure of Example 1 but initially substituting astoichiometrically equivalent quantity of 3-bromoaniline for3,4-dichloroaniline there is obtained3-bromo-N-(2-hydroxycyclopentyl)propionanilide.

Part B

Following the procedure of Example 4 but substituting the3-bromo-N-(2-hydroxycyclopentyl)propionanilide for3,4-dichloro-N-(2-hydroxycyclopentyl)propionanilide there is obtained3-bromo-N-(2-acetoxycyclopentyl)propionanilide.

EXAMPLE 11

Part A

Following the procedure of Example 1, Part B, but substituting astoichiometrically equivalent quantity of cyclopropanecarbonyl chloridefor propionic anhydride, there is obtained3,4-dichloro-N-(2-hydroxycyclopentyl)-cyclopropanecarboxanilide.

Part B

Following the procedure of Example 2 but using a stoichiometricallyequivalent quantity of the starting material from Part A (above) inplace of trans-3,4-dichloro-N-(2-hydroxycyclopentyl)propionanilide,there is obtained3,4-dichloro-N-(2-methoxycyclopentyl)cyclopropanecarboxanilide.

For oral administration either solid or fluid unit dosage forms can beprepared. For preparing solid compositions such as tablets, the compoundof formula I is mixed with conventional ingredients such as talc,magnesium stearate, dicalcium phosphate, magnesium aluminum silicate,calcium sulfate, starch, lactose, acacia, methylcellulose, andfunctionally similar materials as pharmaceutical diluents or carriers.Wafers are prepared in the same manner as tablets, differing only inshape and the inclusion of sucrose or other sweetener and flavor. Intheir simplest embodiment, capsules, like tablets, are prepared bymixing the compound with an inert pharmaceutical diluent and filling themixture into a hard gelatin capsule of appropriate size. Soft gelatincapsules are prepared by machine encapsulation of a slurry of thecompound with an acceptable vegetable oil, light liquid petrolatum, orother inert oil.

Fluid unit dosage forms for oral administration such as syrups, elixirs,and suspensions can be prepared. The water-soluble forms can bedissolved in an aqueous vehicle together with sugar, aromatic flavoringagents and preservatives to form a syrup. An elixir is prepared by usinga hydro-alcoholic (ethanol) vehicle with suitable sweeteners such assugar and saccharin, together with an aromatic flavoring agent.

Suspensions can be prepared with an aqueous vehicle with the aid of asuspending agent such as acacia, tragacanth, methylcellulose and thelike.

For parenteral administration, fluid unit dosage forms are preparedutilizing the compound and a sterile vehicle, water being preferred. Thecompound, depending on the vehicle and concentration used, can be eithersuspended or dissolved in the vehicle. In preparing solutions thecompound can be dissolved in water for injection and filter sterilizedbefore filling into a suitable vial or ampul and sealing.Advantageously, adjuvants such as a local anesthetic, preservative andbuffering agents can be dissolved in the vehicle. To enhance thestability, the composition can be frozen after filling into the vial andthe water removed from vacuum. The dry lyophilized powder is then sealedin the vial and an accompanying vial of water for injection is suppliedto reconstitute the liquid prior to use. Parenteral suspensions areprepared in substantially the same manner except that the compound issuspended in the vehicle instead of being dissolved and sterilizationcannot be accomplished by filtration. The compound can be sterilized byexposure to ethylene oxide before suspending in the sterile vehicle.Advantageously, a surfactant or wetting agent is included in thecomposition to facilitate uniform distribution of the compound.

Rectal suppositories as used herein mean solid bodies for insertion intothe rectum which melt or soften at body temperature releasing one ormore pharmacologically or therapeutically active ingredients.

Pharmaceutically acceptable substances utilized in rectal suppositoriesare bases or vehicles and agents to raise the melting point.

Examples of bases or vehicles include, for example, cocoa butter(theobroma oil), glycerin-gelatin, carbowax (polyoxyethylene glycol) andappropriate mixtures of mono-, di-, and triglycerides of fatty acids.Combinations of the various bases may be used. Agents to raise themelting point of suppositories include, for example, spermaceti and wax.Rectal suppositories may be prepared either by the compressed method orby molding. The usual weight of a rectal suppository is 2.0 g.

Tablets and capsules for rectal administration are manufacturedutilizing the same pharmaceutically acceptable substance and by the samemethods as for formulations for oral administration.

Rectal suppositories, tablets or capsules are packaged eitherindividually, in unit dose, or in quantity, multiple dose, for example,2, 6 or 12.

The term unit dosage form, as used in the specification and claims,refers to physically discrete units suitable as unitary dosages formammals including human subjects, each unit containing a predeterminedquantity of active material calculated to produce the desiredtherapeutic effect in association with the required pharmaceuticaldiluent, carrier, or vehicle. The specifications for the novel unitdosage forms of this invention are dictated by and directly dependent on(a) the unique characteristics of the active material and the particulareffect to be achieved, and (b) the limitations inherent in the art ofcompounding such an active material for use in humans, as disclosed indetail in this specification, these being features of the presentinvention. Examples of suitable unit dosage forms in accord with thisinvention are tablets, capsules, pills, suppositories, powder packets,granules, wafers, cachets, teaspoonsful, tablespoonsful, droppersful,ampuls, vials, segregated multiples of any of the foregoing, and otherforms as herein described.

The dosage of the compound for treatment depends on route ofadministration, the age, weight and condition of the patient. A dosageschedule of from about 4 to about 400 mg., preferably 20 to 200 mg. perday, given in a single dose or in subdivided doses, embraces theeffective range to alleviate depression for which the compositions areeffective. The dosage to be administered is calculated on the basis offrom about 0.08 to about 6 mg./kg. of weight of the subject, preferablyfrom about 0.3 to about 3 mg./kg. The compound is compounded with asuitable pharmaceutical carrier in unit dosage form for convenient andeffective administration. In the preferred embodiments of thisinvention, the dosage units can contain the compound in 10, 25, 30, 50and 100 mg. amounts for systemic treatment. A sterile preparation of theactive material contains 1% to 25% w/v for parenteral treatment. Thedosage of compositions containing a compound of formula I and one ormore other active ingredients is to be determined with reference to theactual dosage of each such ingredient.

In addition to the administration of a compound of formula I as theprincipal active ingredient of compositions for treatment of theconditions desired herein, the said compound can be combined with othercompounds, such as analgesics, for example, aspirin, acetaminophen, PACcompound (phenacetin-aspirin-caffeine), anti-inflammatory agents, suchas ibuprofen, and the like, anxiolytics, such as perphenazine,amitriptylene hydrochloride, chlordiazepoxide, alprazolam, doxepinhydrochloride and the like.

EXAMPLE 12

A lot of 10,000 tablets, each containing 25 mg. oftrans-3,4-dichloro-N-(2-hydroxycyclopentyl)propionanilide as the activeingredient compound, is prepared from the following types and amounts ofingredients:

    ______________________________________                                        Active ingredient compound                                                                              250 g                                               Dicalcium phosphate       1500 g                                              Methylcellulose, U.S.P. (15 cps.)                                                                       60 g                                                Talc                      150 g                                               Corn Starch               200 g                                               Magnesium stearate        12 g                                                ______________________________________                                    

The compound and dicalcium phosphate are mixed well, granulated with7.5% solution of methylcellulose in water, passed through a No. 8 screenand dried carefully. The dried granules are passed through a No. 12screen, mixed thoroughly with the talc, starch and magnesium stearate,and compressed into tablets.

These tablets are useful in reducing depression in adults at a dose of 1to 2 tablets per day, depending on the age and weight of the patient.

EXAMPLE 13

One thousand two-piece hard gelatin capsules, each containing 10 mg. of3-bromo-N-[2-(acetoxy)cyclopentyl]propionanilide as the activeingredient compound, are prepared from the following types and amountsof ingredients:

    ______________________________________                                        Active ingredient compound                                                                              10 g                                                Lactose                   75 g                                                Talc                      25 g                                                Magnesium stearate        1.5 g                                               ______________________________________                                    

The ingredients are mixed well and filled into capsules of the propersize.

Capsules so prepared are useful for treating depression in adults at adose of one to two capsules per day.

EXAMPLE 14

One thousand tablets for sublingual use are prepared from the followingingredients:

    ______________________________________                                        3-Trifluoromethyl-N-[2-(benzyloxy)cycle-                                      pentyl]propionanilide         100 g                                           Active ingredient compound, micronized                                                                      5 g                                             Polyethylene glycol 4000, powdered                                                                          150 g                                           Polyethylene glycol 6000, powdered                                                                          75 g                                            ______________________________________                                    

The ingredients are mixed well and compressed into sublingual-typetablets.

These tablets (each containing 100 mg. of active ingredient) placedunder the tongue are useful to reduce depression with a rapid inductionat a dose of one tablet per 6 hours.

EXAMPLE 15

Soft gelatin capsules for oral use, each containing 30 mg. of3,4-dichloro-N-(2-methoxycyclopentyl)propionanilide, are prepared byfirst dispersing the micronized compound in corn oil to render thematerial capsulatable and then encapsulating in the usual manner. Thesecapsules are useful in treatment of depression at a dose of one to twocapsules a day.

EXAMPLE 16

One thousand tablets, each containing 50 mg. of3,4-dichloro-N-[2-(4-bromobenzoyloxy)cyclopentyl]propionanilide are madefrom the following types and amounts of ingredients:

    ______________________________________                                        3,4-dichloro-[2-(4-bromobenzoyloxy)cyclo-                                     pentyl]propionanilide         50 g                                            Lactose                       355 g                                           Microcrystalline cellulose NF 120 g                                           Starch                        16 g                                            Magnesium stearate powder     4 g                                             ______________________________________                                    

The ingredients are screened and blended together and pressed intotablets.

The tablets are useful to overcome depression.

EXAMPLE 17

A sterile preparation suitable for intramuscular injection andcontaining 50 mg. of 4-bromo-N-[2-hydrocyclopentyl]propionanilide, ineach millititer is prepared from the following ingredients.

    ______________________________________                                        4-Bromo-N-[2-hydroxycyclopentyl]pro-                                          pionanilide                 50 g                                              Benzyl benzoate             200 ml.                                           Methylparaben               1.5 g                                             Propylparaben               0.5 g.                                            Cottonseed oil q.s.         1,000 ml.                                         ______________________________________                                    

One milliliter of this sterile preparation is injected to reducedepression in adults.

EXAMPLE 18

Following the procedure of the preceding Examples 12 through 17,inclusive, unit dosage forms are similarly prepared substitutingequivalent amounts of other formula I compounds, for example, the transisomers of:

3-Chloro-4-methyl-N-(2-hydroxycyclopentyl)propionanilide,

3,4-Dichloro-N-(2-ethoxycyclopentyl)propionanilide,

3,4-Dimethoxy-N-(2-propoxycyclopentyl)propionanilide,

3-Chloro-4-fluoro-N-(2-methoxycyclopentyl)propionanilide,

3,4-Dibromo-N-(2-benzyloxycyclopentyl)propionanilide,

3,4-Dimethyl-N-(2-benzoyloxycyclopentyl)propionanilide,

3,4-Dichloro-N-[2-(4-bromobenzyloxy)cyclopentyl]cyclopropanecarboxanilide,

4-Bromo-N-(2-hydroxycyclopentyl)acrylanilide,

3,4-Dichloro-N-[2-(3,4-dichlorobenzoyloxy)cyclopentyl]propionanilide,

3-Methoxy-N-(2-hydroxycyclopentyl)propionanilide,

3-Chloro-4-methyl-N-[2-(4-chlorobenzyloxy)cyclopentyl]propionanilide,

3,4-Dichloro-N-[2-(4-bromobenzoyloxy)cyclopentyl]acetanilide,

3,4-Dichloro-N-[2-(3-chloro-4-methylbenzyloxy)cyclopentyl]cyclohexanecarboxanilide,

4-Azido-N-(2-hydroxycyclopentyl)propionanilide,

4-Azido-N-[2-(3,4-dichlorophenoxy)cyclopentyl]propionanilide,

4-Azido-N-[2-(3-chloro-4-methylbenzyloxy)cyclopentyl]-n-butanoylanilide,

4-Azido-N-[2-(benzoyloxy)cyclopentyl]acetanilide,

4-Azido-N-[2-(3,4-dichlorobenzoyloxy)cyclopentyl]propionanilide,

4-Azido-N-[2-(propionyloxy)cyclopentyl]cyclopentanecarboxanilide,

4-Azido-N-[2-(allyoxyl)cyclopentyl]methoxyacetanilide, and the like, forthe respective active ingredients in those examples.

What is claimed is:
 1. A compound of the formula ##STR10## wherein theheavy dot (•) at the 1-position carbon atom of the cyclopentyl ringdenotes the trans-configuration relative to the oxygen group (--OR₁) inthe 2-position of the cyclopentyl ring;R is C₁ to C₃ -alkyloxy or C₁ toC₃ -alkyloxymethyl; R₁ is hydrogen, C₁ to C₃ -alkyl, C₃ to C₅-(allyllic)alkenyl, the benzyl group ##STR11## wherein Y' and Z' are asdefined above, or the group ##STR12## wherein R₂ is hydrogen, C₁ to C₃-alkyl, the benzyl group as above, or a phenyl group ##STR13## whereinY' and Z' are as defined hereinbelow; and each of Y and Z or Y' and Z'is selected from the group consisting of hydrogen, a halogen having anatomic number of from 9 to 35, trifluoromethyl, C₁ to C₃ -alkyl, and C₁to C₃ -alkyloxy, and Y, Z, or Y' and Z' are not necessarily the same atthe same time.
 2. A process for treating depression which comprisesadministering to a depressed human a compound of the formula ##STR14##wherein the heavy dot (•) at the 1-position of the cyclopentyl ringdenotes the trans-configuration relative to the oxygen group (--OR₁) inthe 2-position of the cyclopentyl ring;R is C₁ to C₃ -alkyloxy or C₁ toC₃ -alkyloxymethyl; R₁ is hydrogen, C₁ to C₃ -alkyl, C₃ to C₅-(allylic)alkenyl, the benzyl group ##STR15## wherein Y' and Z' are asdefined below, or the group, ##STR16## where R₂ is hydrogen, C₁ to C₃-alkyl, the benzyl group as defined above or the phenyl group ##STR17##wherein Y' and Z' are as defined below, each of Y, Z, Y' and Z' isselected from the group consisting of hydrogen, halogen having an atomicnumber of from 9 to 35, trifluoromethyl, C₁ to C₃ -alkyl, and C₁ to C₃-alkyloxy, and Y, Z, Y' and Z' are not necessarily the same at the sametime, in a non-toxic amount effective to alleviate the conditions ofdepression, in association with a pharmaceutical carrier.
 3. Apharmaceutical preparation in dosage unit form adapted foradministration to obtain an anti-depression effect comprising per dosageunit, an anti-depressant effective, non-toxic amount of a compound ofthe formula ##STR18## wherein the heavy dot (•) at the 1-position carbonatom of the cyclopentyl ring denotes the trans-configuration relative tothe oxygen group (--OR₁) in the 2-position of the cyclopentyl ring;R isC₁ to C₃ -alkyloxy or C₁ to C₃ -alkyloxymethyl; R₁ is hydrogen, C₁ to C₃-alkyl, C₃ to C₄ -(allylic)alkenyl, the benzyl group ##STR19## whereinY' and Z' are as defined below, or the group ##STR20## where R₂ ishydrogen, C₁ to C₃ -alkyl, the benzyl group as above, or a phenyl group##STR21## wherein Y' and Z' are as defined hereinbelow: and each of Yand Z or Y' and Z' is selected from the group consisting of hydrogen,halogen having an atomic number of from 9 to 35, trifluoromethyl, C₁ toC₃ -alkyl and C₁ to C₃ -alkyloxy, and Y, Z, Y' and Z' are notnecessarily the same at the same time.
 4. A composition according toclaim 3 wherein compound of formula I is present in an amount rangingfrom about 4 to about 400 mg. per dosage unit.